3D-QSAR, molecular docking, and ONIOM studies on the structure-activity relationships and action mechanism of nitrogen-containing bisphosphonates

Enantioseparation and mechanism study on baclofen by capillary electrophoresis and molecular modeling

Enantioselective analysis of chiral drugs plays a significant role in chemistry, biology and pharmacology. Baclofen, an antispasmodic chiral drug, has been widely studied due to the obvious differences in toxicity and medical activity between enantiomers. Herein, a simple and efficient method for separation of baclofen enantiomers by capillary electrophoresis was established without complicated sample derivatization and expensive instruments. Then, the molecular modeling and density functional theory were used to simulate and investigate the chiral resolution mechanism of electrophoresis, the calculated intermolecular forces were directly presented by visualization softwares. Moreover, the theoretical and experimental electronic circular dichroism (ECD) spectra of ionized baclofen were compared, and the configuration of dominant enantiomer in the nonracemic mixture can be determined by ECD signal intensity, which was proportional to the electrophoresis peak area difference of the corresponding enantiomer excess experiments. In this way, the peak order identification and configuration quantification of baclofen enantiomers in electrophoretic separation were successfully achieved without relying on a single standard.

Inhibition of zoledronic acid derivatives with extended methylene linkers on osteoclastogenesis involve downregulation of JNK and Akt pathways

Bisphosphonates (BPs), especially zoledronic acid (ZOL), are clinically used to treat osteolytic bone lesions. However, serious side-effects may be also induced during the therapeutic process. To improve the BPs drugs, here, we investigated the effects of a series of ZOL derivatives with increasing number of methylene linker between the imidazole ring and the P-C-P backbone named IPrDP, IBDP, IPeDP, and IHDP on cell viability and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation, function and apoptosis induction in mouse bone marrow-derived macrophages (BMMs). Our results suggested that IPeDP and IHDP, which contains 4 and 5 methylene linkers, respectively, exerted lower toxicity on BMMs compared with ZOL, IPrDP, and IBDP, which contains 1, 2, and 3 methylene linkers respectively. At concentrations below cytotoxicity threshold, IPeDP and IHDP possessed strong abilities of antiosteoclast formation, antibone absorption, and inducing osteoclast apoptosis, which were similar to ZOL and more powerful than IPrDP and IBDP. The mechanism behind these effects of IPeDP and IHDP might involve the interference of small GTPases prenylation through suppression of mevalonate pathway. The downregulation of JNK and Akt phosphorylation and subsequent inhibition of the expression of c-Fos and NFATc1 might also be involved. Our results supported the potential usage of IPeDP and IHDP to treat bone-related disorders involving increased osteoclastogenesis. Our attempt to extend the methylene linker between the imidazole ring and the P-C-P backbone of ZOL also reveals some regularities between the structure and properties of the BPs drugs.

Comparative analysis of interactions between aryl hydrocarbon receptor ligand binding domain with its ligands: a computational study

BACKGROUND

Aryl hydrocarbon receptor (AhR) ligands may act as potential carcinogens or anti-tumor agents. Understanding how some of the residues in AhR ligand binding domain (AhRLBD) modulate their interactions with ligands would be useful in assessing their divergent roles including toxic and beneficial effects. To this end, we have analysed the nature of AhRLBD interactions with 2,3,7,8-tetrachlorodibenzo-ρ-dioxin (TCDD), 6-formylindolo[3,2-b]carbazole (FICZ), indole-3-carbinol (I3C) and its degradation product, 3,3'-diindolylmethane (DIM), Resveratrol (RES) and its analogue, Piceatannol (PTL) using molecular modeling approach followed by molecular dynamic simulations.

RESULTS

Results showed that each of the AhR ligands, TCDD, FICZ, I3C, DIM, RES and PTL affect the local and global conformations of AhRLBD.

CONCLUSION

The data presented in this study provide a structural understanding of AhR with its ligands and set the basis for its functions in several pathways and their related diseases.